One known type of information storage device is a disk drive device. FIG. 1a illustrates a conventional disk drive device 200 and shows a magnetic disk 101 mounted on a spindle motor 102 for spinning the disk 101. A voice coil motor arm 104 carries a head gimbal assembly (HGA) 100 that includes a slider 103 incorporating a read/write head. A voice-coil motor is provided for controlling the motion of the motor arm 104 and, in turn, controlling the slider 103 to move from track to track across the surface of the disk 101, thereby enabling the read/write head to read data from or write data to the disk 101. In operation, a lift force is generated by the aerodynamic interaction between the slider 103 and the spinning magnetic disk 101. The lift force is counterbalanced by spring forces applied by a suspension of the HGA 100 such that a predetermined flying height above the surface of the spinning disk 101 is maintained over a full radial stroke of the motor arm 104.
FIG. 1b shows a bottom plan view of a slider of the disk drive device 200 shown in FIG. 1a. The slider 103 has an air bearing surface (ABS) 117 formed thereon for generating an aerodynamic interaction between the slider 103 and the spinning disk 101 (refer to FIG. 1a) during operation of the disk drive device, thus making the slider 103 flying over the disk 101. The slider 103 further provides a pole tip 113 having a reading/writing head thereon to realize data reading/writing operation with respect to the disk 101.
FIG. 1c shows a detailed structure of the pole tip 113 of the slider 103. As shown in the figure, the pole tip 113 comprises from left to right second a second inductive write head pole 11, a first inductive write head pole 13 spacing away from the second inductive write head pole 11, a second shielding layer 15 and a first shielding layer 16. The components are carried on a ceramic substrate 21 that constitutes main body of the slider 103. A magneto-resistive element (MR element) 14 is provided between the second shielding layer 15 and first shielding layer 16. In addition, copper coils 12 are provided between the first inductive write head pole 13 and the second inductive write head pole 11 for assisting in writing operation. In addition, an overcoat 31 is covered on the ABS to protect the slider 103.
On one hand, since the ABS especially the pole tip region (mainly made of metal material, for example the copper coils 12 described above) of a slider is susceptible to damage caused by chemical corrosion resulting from environment moisture, a protect layer (such as the overcoat 31 described above) is necessary to be coated on the whole ABS of the slider. For this purpose, carbon material such as diamond-like carbon (DLC) that has strong corrosion-resist ability is often utilized as a protector layer. In addition, it is expected that adhesion ability of the DLC layer with respect to the ABS is as strong as possible so that the DLC layer will not be easily peeled off from the ABS. On the other hand, it is desired to reduce thickness of the DLC layer covered on the ABS so as to further reduce the flying height of the slider (the distance between the disk and the ABS of the slider), thus making it possible to further improve storage capacity of a disk drive device. Various methods for coating a DLC layer are available currently; however, all these methods fail to meet both requirements, i.e., strong adhesion ability and small thickness. These methods are described below.
FIG. 2 illustrates such a conventional method. The method comprises the steps of: firstly, providing sliders arranged in arrays, each slider comprising an ABS (step 201); then, forming a silicon layer on the ABS of each slider (step 202); finally, forming a DLC layer on the silicon layer (step 203). Due to natural properties of DLC, it is difficult to directly deposit the DLC on the ABS, especially on the pole tip thereof with sufficient adhesion force; as a result, for improving adhesion ability, a silicon layer, which helps enhance adhesion ability of the DLC layer on the ABS, is coated on the ABS before coating of the DLC layer, and then, the DLC layer is coated on the silicon layer.
Though the DLC layer coated by above method is stable in adhesion ability, however, as two layers of different materials, but not only one layer of material are coated altogether, it is difficult to further reduce total thickness of the silicon layer and the DLC layer, because further reduction in thickness of either the silicon layer or DLC layer will cause respective layer to be discontinuous in coverage, thus increasing likelihood of the DLC layer being peeled off from the ABS. This discontinuity coverage of the layer can be checked and evaluated using acid dipping method. In the method the corrosion dots on the discontinuous layer caused by acid corrosion are found under a high magnification microscope.
Another method for forming a DLC layer on ABS of a slider is directly coating a DLC layer on the ABS of a slider. In the method, only a single DLC layer but not the combination of a silicon layer and a DLC layer is deposited on the ABS, thereby little even no problem of discontinuity in thickness of a single material layer exists, thus the total thickness of the DLC layer capable of being further reduced such that the flying height of the slider can be further reduced. However, this method is impracticable. Such coated DLC layer will be easily delaminated from the ABS after some kind of tests, because as discussed above, the adhesion of the DLC layer to the slider ABS, especially on the pole tip region is weak.
Thus, there is a need for an improved DLC coating method that does not suffer from the above-mentioned drawbacks.